The present disclosure relates to the art of lighting fixtures, and more particularly to area lighting fixtures for distributing patterns of light on the ground. These lighting fixtures can be used for area lighting, including street, parking lot, walkway, bicycle path, or other similar applications. Additionally, these lighting fixtures can be employed for indoor applications, such as, illuminating basketball or factory building floors.
In general, lighting fixtures consist of a lamp or other light source, and a reflector for reflecting light from the light source. The shape of the reflector and any shielding typically define the light distribution pattern. More particularly, the light pattern is either controlled by external shielding, for high intensity discharge lamps, or by an optical package for light emitting diode packages. Since shielding is an inefficient blocking of otherwise useable light, the HID solution wastes light power that is not directed in the desired direction.
Light energy spreads over distance. The illumination of a remote area therefore varies inversely as the square of the distance from the light source. Additionally, since light fixtures directing light to a relatively large target area, the light source is many times smaller than the area to be lighted. Accordingly, the beam of light energy produced by each fixture must be relatively intense to cover a substantial area.
These characteristics present certain lighting problems. First of all, to maintain a given light level at a distant target area, the light source must produce a much higher level of light energy at the source. This can contribute to glare problems for those viewing the fixtures. Secondly, the use of diverging or converging beams can result in a significant amount of light falling outside the target area. This results in spill. Spill and glare are inefficient use of the light and are frequently objectionable.
Spill in parking, street and highway lighting results in wide-scale lighting of areas, which makes the actual roadway less distinct from surrounding areas. Additionally, lack of control also translates, in many applications, into the utilization of more light poles and lighting fixtures, which is expensive and consumes substantial resources.
Also, most existing light systems have broadcast or spread light over as much of the highway or roadway as possible. However, by doing so, some light is most times projected toward the driver rather than away from the driver in the driver's viewing direction for each lane of the highway. This can contribute to glare for drivers on the roadway.
In certain environments, square distribution lighting fixtures may be preferred by lighting architects. To illuminate a parking lot, for example, the lighting architect can employ fewer lighting fixtures because overlap of distribution patterns can be eliminated. Additionally, lighting architects can eliminate spill at the corners and edges of the parking lot by using a square lighting distribution. Alternatively, round or oval light distributions can be the most efficient wherein little or no shielding of light is necessary.
Having a light engine which is selectively modifyable to provide a wide array of light distribution patterns allows precise control of light. One advantage of the present disclosure is that by providing an adaptable modular lighting fixture, it is feasible to readily select fixture modules having suitable light distribution and orientation to properly light almost any area or shape with minimal spill and limited viewer glare.